em3ev bulk chargers with switches

does anyone who has one of their controllers with the switches to pick 100% 90% or 50% SOC ever opened it up to see how their switch changes the output voltage? I'm trying to see if its worth buying their bulk charger or if its just a switch with an inline resistor.

I won't say I understand what the circuit does, but each switch goes to a different pot on a daughter board. So you can adjust the voltage setting of each switch position some. Also on the board is a 4th, very touchy pot that controls output amps.

The daughter board is fairly solidly attached, not a huge risk for bending and shorting if you carry the charger around some. I've had that happen with less well attached daughter boards on chargers. I still wouldn't actually mount it to a vehicle, but mine has stood some carrying in a pannier. I have found that if I carry it around, I will have to adjust the output pot from time to time. A good bump can move it enough to matter.

I definitely give the charger two thumbs up. I don't use the storage charge mode all that much, but I love charging my 14s packs to 4.1v quickly and easily. I did turn down the highest setting to about 4.15v, so I get a bit more wiggle room on a charge that is close to 100%. I found 4.1v sacrificed too much range on some trips, but didn't like any charging to 4.2v on my new HK packs.

I often charge to 4.1v the night before a ride, then give it the last .5v in the morning before I head out.

I have one too, not opened it up or used it in anger yet. It was listed on the site for 21s but at my request Paul has reset the voltages for 20s so as DM says all the voltages can be adjusted independently. I don't know how much adjustment is available, mine has been turned down about 5%.

I know this is replying to a very old post. But I thought it might be helpful for others.

Sharing some knowledge on the EM3ev 5A charger with pics too (see below), and I have one question I really need an answer to. Please help!

I opened up (very easily, with 8 screws) the EM3ev 5A charger to set the charge voltages for my battery, to gain the following charge settings for different switch positions:
* Low switch: 56% 3.82v/cell 53.48v
* Middle switch: 80% 4.04v/cell 56.56v
* High switch: 90% 4.11v/cell 57.54

These were calculated specifically to my battery pack using:
http://www.ebikes.ca/tools/charge-simulator.html

There were 4 potentiometers (pots) in the charger, which I had to work out by trial and error which pot changed what switch position's voltage. This is what I found out:

• * Pot functions (when facing pot screwface):
  * far left changes lowest voltage only (switch position I)
  * second from left changes HIGHEST voltage only (switch position II)
  * third from left, turn left to increase v (changes ALL voltages of all three switch positions, so use this first to get the middle switch voltage right, then the other two to adjust top and bottom)
  * farthest on right does NOTHING to voltage (might be amps!?) I adjusted slightly a bit to test, and turned back to where i THINK it was originally, to within a couple of degrees angle.

So, here is my question: In the pics, you see the four blue pots. What on earth would the far right one do, from what you can see here! I tried to get as much detail in the pics as possible. I might have slightly changed this pot position, but I don't know what affect that has... Bit scary to use it now, without knowing.

Here are the pics: http://imgur.com/a/Yuksq

Ughh,, brain damaged,,, I think that last pot is amps. But I can't really remember shit good from when I was really sick.

The amps pot on mine is incredibly touchy btw, so I've re set it a few times. To set it, you need an empty battery and a watt meter.

thanks so much for your reply. Would you mind to detail how you set it? What were you looking for as you set it?

What amps should it be? My battery is 30%, so I assume that is "empty" enough.

I'm concerned that it has somehow screwed with the amps, and the CACV ration - is this possible?

Do i need to monitor the amps all the way through the charge process? I have a good multimeter than can measure current, so have the tools - just need to know what I am looking for, what is "correct"?

I have two of these, which I was running in parallel. One stopped working after 10-15 charges. It reads 38.9 volts in any of the switch positions and, not surprisingly, won't start charging when plugged into the battery. Anybody on here have a clue what is wrong?

Warren said:

I have two of these, which I was running in parallel. One stopped working after 10-15 charges. It reads 38.9 volts in any of the switch positions and, not surprisingly, won't start charging when plugged into the battery. Anybody on here have a clue what is wrong?

Click to expand...

Did the 110v-240v switch accidentally get bumped? That causes what you described, so I have heard.

maltokyo,

"Did the 110v-240v switch accidentally get bumped? That causes what you described, so I have heard."

When they first arrived, I didn't realize they had a 120-240v switch. The first one I tried didn't charge, the first time I plugged it in. Looking around, I found the switch. It worked correctly after that. I have no idea if that is the one that later failed. I just tried checking it in the 240v position. The charger reads 43.9v in any of the three positions.